Field of the Invention
The present invention relates to fluidic circuits and nozzle assemblies configured with fluidic circuit oscillators, and more particularly to fluidic nozzle and circuit assemblies configured to generate a spray for automotive, industrial and consumer applications.
Discussion of the Prior Art
A fluidic nozzle creates a stream of fluid that oscillates within an included angle, known as the fan angle, as illustrated in FIGS. 1A-1C. The distribution of the fluid within this fan will vary depending on the type of fluidic circuit used. For example, in the mushroom circuit disclosed in applicant's U.S. Pat. No. 7,267,290, the oscillating stream will tend to dwell briefly at the extremes of its travel, creating a fluid distribution or spray pattern that is called a heavy-ended fan as illustrated in FIG. 1E. Some circuits may include a splitter, which can increase the maximum fan angle and spray velocity. In this case, the oscillating stream will tend to dwell on the splitter, causing a fluid distribution or spray pattern that is called a center-heavy fan.
The fluid distribution can be important in several applications for fluidic nozzles. In an irrigation nozzle, for example, it is desirable to distribute water evenly over a given area or shape (for example, a quarter circle.) If a heavy-ended fluidic were to be used in such a case, more fluid would be deposited on the edges of the spray, and less in the center. Furthermore, since the trajectory of the droplets is related to droplet size and velocity, the irrigation nozzle will tend to throw water further on the ends than in the middle. Many irrigation nozzle assemblies have spray patterns with several heavy bands.
Another common application for fluidic nozzles is to distribute windshield cleaning fluid across a windshield. In this case, parts of the windshield may be covered with large amounts of wiper fluid, while other parts get only a light coating. In many cleaning applications, it is desirable to distribute fluid as evenly as possible over specific areas.
For contemporary automotive applications (e.g., as discussed generally in applicant's commonly owned U.S. Pat. Nos. 7,014,131, 7,267,290 and 7,651,036) windshield washer nozzles are needed with improved dynamic performance, which means automotive windshield washing system designers want sprays having large droplets delivered at higher velocities to withstand high speeds when the car is in motion. This characteristic is referred to as dynamic performance. Additionally, the spray nozzle needs to work with cold liquid mixtures (e.g., typical windshield washer fluids comprising methanol/ethanol water mixes). This characteristic is referred to as cold performance.
For an illustrative example of how a fluidic oscillator or fluidic circuit might be employed, as shown in applicant's U.S. Pat. No. 7,651,036 and illustrated in FIGS. 1A-1F, a nozzle assembly 10 is configured with a housing which defines a substantially hollow fluid-impermeable structure with an interior lumen and one or more ports or slots 20, each defining a substantially rectangular passage or aperture with smooth interior slot wall surfaces 22. The interior sidewall surfaces 22 are preferably dimensioned for cost effective fabrication using molding methods and preferably include sidewall grooves positioned and dimensioned to form a “snap fit” with ridges or tabs in a mating fluidic circuit insert (e.g., 18). Nozzle assembly 10 can be configured to include one or more fluidic circuit inserts or chips which are dimensioned to be tightly received in and held by the slot 20 defined within the sidewall of the housing. When fluidic circuit insert 18 is fitted tightly within port or slot 20, the nozzle assembly provides a channel for fluid communication between the housing's interior lumen and the exterior of the housing so that fluid entering the housing's interior lumen may be used to generate an oscillating spray directed distally and aimed by the orientation and configuration of the housing, but better cold performance and spray velocity are needed. Prior art windshield washer systems do not provide adequate dynamic performance (or spray velocity) and cold performance for some applications.
There is a need, therefore, for a durable, reliable and cost effective nozzle structure and fluid distribution or spray generation method to broaden the dynamic and cold performance envelope for nozzle assemblies to be used in automotive, industrial and consumer applications.